Safe and automatic method for removal of coke from a coke vessel

ABSTRACT

A closed system that eliminates worker exposure during coker vessel decoking operations and thereby significantly reduces risks to workers also increase coking capacity by reducing the coking cycle time. The closed system preferably comprises a coker vessel with a side entry feed line attached to the vessel above the vessel bottom; a closure housing with laterally moveable closure member therein sealed to the vessel bottom either directly without, or indirectly with an adapting spool member and; a coke chute sealed to the bottom of the closure housing. The system can be remotely and repetitively operated through numerous coking/decoking cycles without removal of any system element.

FIELD OF THE INVENTION

[0001] The present invention relates to the field of hydrocarbonprocessing and, in particular, to heavy hydrocarbon processing in cokevessels.

BACKGROUND OF THE INVENTION

[0002] Many oil refineries recover valuable products from the heavyresidual hydrocarbons (commonly referred to as resid or residuum), whichremain following initial refining, by a thermal cracking process knownas delayed coking. Generally, the delayed coking process involvesheating the heavy hydrocarbon feed from a fractionation unit, thenpumping the heated heavy feed into a large steel vessel commonly knownas a coke drum. The unvaporized portion of the heated heavy feed settlesout in the coke vessel where the combined effect of retention time andtemperature causes the formation of coke. Vapors from the top of thecoke vessel, which typically consist of steam, gas, naphtha and gasoils, are returned to the base of the fractionation unit for furtherprocessing into desired light hydrocarbon products. The operatingconditions of delayed coking can be quite severe. Normal operatingpressures in coke vessels typically range from 25 to about 50 pounds persquare inch and the heavy feed input temperature may vary between 900°F. and 950° F. The coke drums operate in pairs, with one drum feedingresiduum and the other drum undergoing the “decoking” sequential steps.The drums typically operate on a cycle, switching every 12-30 hours.

[0003] Coke vessels are typically large, cylindrical vessels commonly 19to 30 feet in diameter and two to three times as tall having a top headand a funnel shaped bottom portion fitted with a bottom head and areusually present in pairs so that they can be operated alternately. Cokesettles out and accumulates in the vessel until it is filled to a safemargin, at which time the heated feed is switched to the empty “sister”coke vessel. Thus, while one coke vessel is being filled with heatedresidual oil, the other vessel is being cooled and purged of hundreds tothousands of tons of coke formed in the vessel during the previousrecovery cycle. The full vessel is isolated, steamed to removehydrocarbon vapors, cooled by filling with water, drained, opened, andthe coke is removed.

[0004] Coke removal, also known as decoking, begins with a quench stepin which steam and then water are introduced into the coke filled vesselto complete the recovery of volatile, light hydrocarbons and to cool themass of coke. The vessel is then vented to atmospheric pressure.Decoking is accomplished at most plants using a hydraulic systemconsisting of a drill stem and drill bit that direct high pressure waterjets into the coke bed. To cut coke in this manner the top and bottomheads of the vessel must be removed. A rotating combination drill bit,referred to as the cutting tool, is about 18 inches in diameter withfour (4) nozzels and is mounted on the lower end of a long hollow drillrod about 6 inches in diameter. The drill bit is lowered into thevessel, on the drill stem, through a flanged opening at the top of thevessel. A “bore hole” is drilled through the coke using the four nozzlesangled approximately 60 degrees down from horizontal. This creates ahole from about 3 to 6 feet in diameter for the coke to fall through.There is normally a naturally occurring small hole in the coke bed forthe initial pass because the resid flows in from the bottom and outtoward the edges of the vessel.

[0005] When the initial bore hole is complete, the drill bit is thenmechanically switched to two (2) horizontal nozzles in preparation forcutting the “blow” hole, which extends to the full drum diameter. Thenozzles shoot jets of water horizontally outwards, rotating slowly withthe drill rod, and those jets cut the coke into pieces, which fall outthe open bottom of the vessel, into a chute that directs the coke to areceiving area. At some plants the hydraulic drill is raised slowly upfrom the bottom the entire vertical height of the coke mass, at othersthe drill is lowered from the top through the mass and at still otherplants the coke mass is first cut from the bottom cone of the vessel andthe remainder is cut from the top of the vessel. In any case, the cutcoke falls out the opening at the bottom of the vessel into the cokechute system. The drill rod is then withdrawn out the flanged opening atthe top of the vessel. Finally, the top and bottom of the vessel areclosed by replacing the head units, flanges or other closure devicesemployed on the vessel unit. The vessel is then clean and ready for thenext filling cycle with the heavy hydrocarbon feed.

[0006] The process of removing and replacing the removable top head andbottom units of the vessel cover is called heading and unheading ordeheading. It is dangerous work, with several risks associated with theprocedures. There have been fatalities and many serious injuries. Thereis significant safety risk from exposure to steam, hot water, fires andrepetitive stress associated with the manual unbolting work.Accordingly, the industry has devoted substantial time and investment indeveloping semi-automatic or fully automatic unheading systems, withattention focused on bottom unheading where the greatest safety hazardis present.

[0007] There are two typical and commonly used methods to move thebottom head out of the way of the falling coke. The first is tocompletely remove the head from the vessel, perhaps carrying it awayfrom the vessel on a cart. This process may be automated as set forth inU.S. Pat. No. 5,336,375. The other way of “removing” the bottom head isto swing it out of the way, as on a hinge or pivot, while the head isstill coupled to the vessel as in U.S. Pat. No. 6,264,829. Several U.S.patents disclose various methods and apparatus for detaching andlaterally moving a drum head or swinging away a drum head including:U.S. Pat. No. 6,264,829 (discloses a swing away hydraulically operateddrumhead adapted for low headroom situations); U.S. Pat. No. 6,254,733(depicting in the drawings a hydraulically removable drumhead); U.S.Pat. Nos. 6,066,237 and 5,876,568 (disclosing an apparatus forsemi-automatically clamping and unclamping a drum bottom head); U.S.Pat. No. 5,947,674 (a drum head device removed by vertically orientedhydraulic cylinders adapted for lowering the head unit and moving itlaterally aside); U.S. Pat. No. 5,785,843 (claims a process involving aswing away hydraulically operated drumhead adapted for low headroomsituations); U.S. Pat. No. 5,581,864 (a remotely operated carriagemounted drumhead removal system); U.S. Pat. No. 5,500,094 (car mounteddrumhead removal system that is horizontally movable); U.S. Pat. No.5,228,825 (a device and method for deheading a drum comprising, in part,a cradle that holds the drum head for removal); U.S. Pat. No. 5,221,019(a remotely operated cart removal system); U.S. Pat. No. 5,098,524 (apivotally attached unheading device associated with clamps); U.S. Pat.No. 4,726,109 (a platform device lowers the drumhead and moves itlaterally away). These systems all use a manual or semi-automaticbolting system that must be uncoupled with every decoking cycle.

[0008] The above described bottom head removal systems all require thatthe heated feed enter the coke vessel from the bottom through the centerof the bottom head. Although in past years there have been some sideentries used, except for possibly one or two cases, side entry use hasbeen discontinued in coker vessels built and put into operation in thelast 20 to 30 or more years. Thus, in the usual coker operation, toremove the vessel bottom head for decoking the feed line must first bedisconnected before the bottom head can be removed. Lastly a coke chutemust be manually or hydraulically moved into place and, typically,safety bolts are manually inserted to secure the chute to the drum,allowing the chute to receive the falling coke. The chute directs thecoke, as it is drilled out of the vessel, to a receiving area where itis later removed. These methods still require the feed line to be openedup and the head removed before the bottom chute can be brought up andattached to the bottom flange of the vessel.

[0009] Considering that there is exposure to personnel and/or equipmentwhen opening the feed line, and considering there is exposure topersonnel and/or equipment when opening the bottom head before the chutecomes up and is attached, and considering there may still be personnelexposure to steam/hot water between the chute and bottom head after thechute is up, improvements in coke vessel bottom unheading system toallow safe removal of coke from the vessel is highly desirable. Theobject of the present invention is to address this need.

SUMMARY OF THE INVENTION

[0010] According to the present invention, a process and apparatus areprovided for repetitively producing and removing coke from a delayedcoker vessel without unheading the vessel bottom, wherein the cokervessel has a bottom portion having an aperture through which coke isreleased, comprising: (a) sealing an aperture closure housing to thebottom portion of the coker vessel; (b) moving a closure member withinthe closure housing to close the aperture; (c) feeding a heavyhydrocarbon feed into the coker vessel through a feed line attached tothe coker vessel at a position above the bottom of the coker vessel; (d)coking the heavy hydrocarbon in the coker vessel; (e) moving the closuremember within the closure housing to open the aperture to allow cokeremoval from the coker vessel; (f) releasing coke through the apertureinto a coke chute, and; repeating steps c through f, successively. In apreferred embodiment of the invention the closure member is poweractuated, such as hydraulically, by remote means, thus obviating anyneed for personnel to be physically present in the vessel bottom areaduring decoking operations.

[0011] The delayed coker vessel of the present invention comprises avessel having a top opening and on the lower portion a side aperture anda bottom aperture; a feed pipe fitted to said side aperture; a bottomaperture closure housing sealed to the bottom aperture; a closure membermoveable within said closure housing; a coke chute sealed to the bottomportion of the closure housing for directing material from the vessel toa receiving area. The combination of the closure housing and moveableclosure member therein is herein termed a closure unit or valve. In oneembodiment of the invention the bottom portion of the coker vessel isdesigned and fabricated to be directly sealed to the closure unit,whereas in another embodiment, particularly useful for retrofittingexisting coker vessels, a bottom transition piece, herein termed aspool, is interposed between the vessel bottom and the closure unit andpressure-tightly sealed to both. In either of these two embodiments, apreferred feature is that the closure housing is pressure-tightly sealedto either (a) the coker vessel or (b) the spool piece. Preferably thepressure-tight seals will withstand pressures within the range of about100 psi to 200 psi, preferably within the range of about 125 psi toabout 175 psi and most preferably between about 130 psi to about 160 psiand thereby preclude substantial leakage of the coker vessel contentsincluding during operation thereof at temperature ranges between about900° F. and 1000° F. In embodiment (b) the spool preferably has a sideaperture and flanged conduit to which the hydrocarbon feed line isattached and sealed.

[0012] The present invention substantially reduces or eliminates thedangerous and time consuming procedure of heading and unheading delayedcoker vessels, thus rendering the decoking procedure safer for personnelto perform by insulating them from exposure to tons of hot, fallingcoke, high pressure steam, scalding water, mobile heavy equipment andother extreme hazards. Among other factors, the present invention isbased on our conception and finding that coke is safely and efficientlyremoved from a delayed coker vessel by the closed system processdescribed herein, sometimes visualized by us as a “closed-pipe” system,which includes side entry for the feed to the vessel and apressure-tight seal between a closure housing for a vessel bottomaperture. The vessel bottom aperture, which opens and closes, preferablyincludes automatic and remote operation of a closure unit, such as avalve, located at the bottom of the coker vessel rather than unboltingand removing or swinging away a “head” as in the prior art. One aspectof enabling the process of the present invention is introducing theheated hydrocarbon feed to the coker vessel at a location above andlateral to the coker vessel bottom and the closure unit, in combinationwith the above mentioned pressure-tight seals.

[0013] A preferred embodiment of the present invention is additionallybased on our finding that coke removal in the present process isadvantageously carried out using a coke chute bolted andpressure-tightly sealed to the bottom of the closure housing. The chute,which preferably remains attached without removal throughout repetitivecoking/decoking cycles, assists in directing coke removed from the cokervessel to a coke receiving area.

[0014] According to a preferred embodiment, the invention furtherrelates to a method and apparatus for automatically opening and closinga vessel bottom aperture by means of a closure unit or valve, in lieu ofthe removable or partially removable head devices described in the priorart, and without the associated safety and efficiency drawbacksdiscussed above. In a preferred embodiment, which takes the place of theprior art removable closure flanges, spool pieces bolted to stationaryvessel flanges, hinged flanges, carts, carriages and the like, powereddevices, which may be controlled automatically, move closure a closuremember within a closure housing between open and closed positions. Thesepowered devices may comprise any powered actuators, including motors,solenoids, or the like, but preferably comprise linear actuators such ashydraulic or pneumatic cylinders with reciprocating piston rods. Suchactuators may be mounted on the vessel the closure housing or otherstationary location to reversibly and repetitively move the closuremember from an open to closed position. Preferably the method of theinvention does not typically require direct human intervention inproximity to the vessel bottom to actuate the powered devices, which ispreferably accomplished by remote instrumentation means such as anelectronic relay system or computer controlled system. The entireprocess is, thus, done safely and without significant or dangerousphysical effort.

[0015] Although secondary to the significant safety improvements, thepresent invention also speeds up the procedure so that thecoking/decoking cycle time can be substantially reduced, withoutcompromise in safety or human effort. The invention also renders theaddition of this new closure device onto the hundreds of existing cokervessels to a relatively simple, quick, and inexpensive procedure, ascompared to the difficult, expensive, and time consuming requirement ofthe existing methods and devices of the prior art described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a schematic diagram of the delayed coking process of thepresent invention. FIG. 2 is a side view of a typical coke vessel bottomknown in the prior art depicting the typical bottom entry feed,removable vessel bottom head in one of the known arrangements anddetachable coke chute arrangement in one of the known arrangements. FIG.3 is a side view depiction of a preferred embodiment of the presentinvention illustrating a coker vessel designed and fabricated to bedirectly attached and sealed to the closure housing and the side entryhydrocarbon feed line. FIG. 4 is a side view depiction of anotherembodiment of the invention, particularly useful for retrofittingexisting coker vessels, showing a spool or flange interposed between thecoker vessel bottom and the closure housing. FIGS. 3 and 4 additionallydepict a coke chute affixed and sealed to the closure housing bottom.FIGS. 5 and 6 depict top and side views of the coke vessel closure unitwith cut-a-way portions showing the movable closure member within theclosure housing.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The invention relates to an improved method of repetitivelycoking heavy hydrocarbons in a coker vessel and repetitively decokingthe vessel in a rapid, safe and efficient manner by simply opening andclosing a closure member, such as a valve, within a closure unit, ratherthan removing or swinging away a bottom head unit, as in the prior art.As generally depicted in FIG. 1, delayed coking is accomplished bycharging hot, resid oil feed through a feed line 10 to the fractionator15 above the bottom vapor zone 20. Lighter hydrocarbon materials such asnaphtha, gases, diesel and gas oils are taken from upper portions of thefractionator vessel 15 by appropriately placed conduits 25, 30, 35 androuted to other facilities for further refining.

[0018] Fresh feed and recycled feed from the bottom of the fractionator15 are pumped through a coker heater 40 where the combined feed isheated to a temperature ranging between about 900° F. to 1000° F.,preferably to between 905° F. to 950° F. and most preferably to between910° F. and 935° F., partially vaporized and alternatively charged toone of a pair of coker vessels 45, 45 a via a feed line 50, 50 alaterally attached to the coker vessel 45, 45 a. Hot vapors from the topof the coker vessels 45, 45 a are recycled to the bottom of thefractionator 15 via a feed line 55. In this manner, the hot vapors fromthe coke vessel are quenched by the cooler feed liquid, thus preventingany significant amount of coke formation in the fractionator 15 andsimultaneously condensing a portion of the heavy ends which are recycledto the coker vessels 45, 45 a. The unvaporized portion of the cokerheater effluent settles out (cokes) in the active coker vessel 45, 45 awhere the combined effect of temperature and retention time results incoke formation. Coke formation in the coker vessel 45, 45 a iscontinued, typically between about 12 to about 30 hours, until theactive vessel 45, 45 a is full to within a safe margin from the vesseltop.

[0019] Once the active coke vessel 45, 45 a is full, the heated heavyhydrocarbon feed is redirected to the empty coker vessel 45, 45 a wherethe above described process is repeated. Coke is then removed from thefull vessel by first quenching the hot coke with steam and water, thenopening a closure unit 60 sealed to the vessel bottom, hydraulicallydrilling the coke from the top portion of the vessel and directingdrilled coke from the vessel through the open closure unit into a cokechute 65 sealed to the bottom of the closure unit 60 to a coke receivingarea 62. Opening of the closure unit is safely accomplished by aremotely located control unit 70.

[0020] Key features of the coking method and coker vessel of thisinvention include the side entry feed line 50 a and 50 b (see FIGS. 3 &4), the closure unit 60, with a moveable closure member therein,pressure-tightly sealed to the vessel bottom 45, 45 a and a coke chute65 pressure-tightly sealed to the bottom of the closure unit 60. Theside entry feed line 50 b can be attached to the vessel side from about6 inches to about 5 feet above the vessel bottom, preferably from 1 footto about four 4 feet from the vessel bottom and most preferably from 1.5feet to 2.5 feet from the vessel bottom.

[0021] Referring to FIGS. 3 and 4, said pressure-tight seals areaccomplished in one preferred embodiment (FIG. 3) preferably by means ofa gasket 90 interposed between facing flanged surfaces of the cokevessel bottom 75, the closure unit 75 a and the coke chute 75 b and theclosure unit 75 c. In another preferred embodiment (FIG. 4), a spoolpiece 80 is used to adapt coke vessel bottom apertures and closure unit60 apertures of different diameters. In this embodiment saidpressure-tight seals are preferably accomplished between facing flangedsurfaces of the coke vessel bottom 75, the spool piece 85, the closurehousing 75 a, the spool piece 85 a and the coke chute 75 b and theclosure unit 75 c. To form the pressure tight seals between said flangedsurfaces preferably the mating surfaces of the respective flanges aremachined to a desired finish, then pressure-tightly joined together witha plurality of suitable fasteners, such as bolts, clamps or similarmeans and with a carefully selected gasket 90 interposed between saidmating surfaces. Similarly, to form the pressure tight seals between theflanged surfaces of the closure housing bottom 75 c and the coke chute75 b preferably the mating surfaces of the respective flanges aremachined to a desired finish, then pressure-tightly joined together witha plurality of suitable fasteners, such as bolts, clamps or similarmeans and with a carefully selected gasket 90 interposed between saidmating surfaces. The method for sealing the coke chute 65 to the closureunit bottom may be different from the method for sealing the vessel orspool to the closure unit top because operating conditions are not acritical factor for seal integrity.

[0022] According to a more detailed embodiment, preferably, said flangedsurfaces are first machined to an RMS (root mean squared) finish rangingfrom 50 to 400, preferably 100 to 300 and most preferably between about120 to 130. An annular gasket comprised of a metal core, such asstainless steal, and a flexible material suitable for use as a gasket incombination with metal under temperatures ranging from −50° F. to 1000°F. and pressures ranging from 100 psi to 200 psi is fitted to one of theflanged surfaces of each of the coke vessel bottom 75, the spool piece85, 85 a and the closure housing 75 a. With the gasket interposedbetween each, the coke vessel bottom 45, and the closure housing 60 (andin another embodiment the spool piece 80) are pressure-tightly joinedtogether by a plurality of suitable fasteners, such as bolts, clamps orsimilar means. The fastening means, such as bolts, clamps or similarmeans are tightened or torqued such that the pressure placed on thegaskets 90 ranges between 10,000 PSI to 30,000 PSI, preferably between15,000 and 25,000 PSI and most preferably 20,000 PSI. Preferably, saidtorque pressure is applied evenly around the gasket circumference.

[0023] In a preferred embodiment of the present invention the metalgasket is annular and stainless steel ranging in thickness from about0.020″ to 0.140′, preferably about 0.024″ to about 0.035″ and mostpreferably from about 0.028″ to about 0.032″, and is concentricallycorrugated. Said corrugations range in height above the metal surface ofthe gasket from a minimum of about 0.001 inches to a maximum of about0.050 inches, preferably from a minimum of about 0.005 inches to amaximum of about 0.030 inches and most preferably from a minimum ofabout 0.010 inches to a maximum of about 0.020 inches. Once corrugated,the width of the gasket is such that the outside and inside diametersthereof are respectively coincident with the outside and inside diameterof the flanged surfaces of the coke vessel bottom, the spool piece, theclosure unit and the coke chute. Flexible graphite material, such asPolycarbon flexible graphite Grade B or BP (with antioxidant inhibitor)or Union Carbide flexible graphite grade GTB or GTK (with antioxidantinhibitor), is bonded to the upper and lower surfaces of the gasketmetal core such that the gasket is sandwiched between the layers ofgraphite material. Thickness of the graphite material can range fromabout 0.005 inches to about 0.030 inches, preferably between 0.010inches to about 0.025 inches and most preferably is about 0.015 inchesthick. Preferably the graphite covering will have the same nominalinside and outside diameter dimensions of the metal gasket. Upon bondingto the gasket metal core surfaces, the corrugations thereof should becovered by the graphite material. Sealing the flanged surfaces of thecoker vessel, the spool piece, the closure unit and, optionally, thecoke chute in the manner described above results in a pressure-tightseal that tolerates the differential expansion that occurs between theflanges during the repetitive coking/decoking cycles of the presentinvention.

[0024]FIGS. 3 and 4 depict preferred embodiments of the coker vessel.FIG. 3 depicts the lower portion of a coker vessel 45 which can be 15 to30 feet in diameter and 80 to 100 feet tall, which is typically cone orfunnel shaped on the lower end and which is attached to a lower flange75 that is typically 60 to 72 inches in diameter. A closure unit 60 ispressure-tightly attached or sealed to the lower flange 75. The closureunit 60 has a flanged lower portion 75 c, which is pressure-tightlyattached or sealed to a coke chute 65. The closure unit 60 and cokechute 65 remain sealed in place during repetitive coking and decokingcycles, but can be detached and laterally moved away from the vessel 45for maintenance via a gantry system, trolley system, rail mounted cartor carriage or other similar system. The number of coking cyclerepetitions that can be carried out prior to breakdown of the system formajor maintenance can vary from 10 to 150 cycles, preferably 20 to 100cycles and, most preferably, from 30 to 75 cycles per pair of vessels.

[0025]FIG. 4 depicts another embodiment of the invention that isparticularly suitable for retrofitting existing coker vessels. As in thefirst embodiment the coke vessel 45 is typically cone or funnel shapedon the lower end which is attached to a lower flange unit 75 that istypically 48 to 72 inches in diameter, preferably 60 to 72 inches indiameter. Interposed between the lower flange 75 and the closure housing60 is a spool piece 80 having a flanged top 85 and bottom 85 a and alaterally attached flanged conduit 50 b for attachment to the heavyhydrocarbon feed line 50 a. The spool piece 80, in one embodiment, canbe of equal diameter on the top and bottom or, in another embodiment,conical in shape to adapt the coker vessel opening diameter to theclosure unit opening diameter, for example a vessel opening of about 72inches and a closure unit opening of about 60 inches in diameter.

[0026]FIGS. 5 and 6 respectively depict plan and side cut-away views ofthe closure unit of a preferred embodiment of this invention. Theclosure unit 60 of this invention is a slide, gate, knife, ball, wedgeplug or similar type valve comprising a closure housing 115 defining aninterior void wherein a closure member 120 is mounted to an actuator oractuators 125, such as hydraulic pistons 130 such that said closuremember can be laterally moved to an open or closed position. The closurehousing further comprises a first end section 135, a second end section140 and a middle section 145 which middle section defines an aperture150 that can range in size from 48 to 72 inches in diameter. When movedlaterally within the closure housing 115 the closure member 120 opensand closes said aperture 150.

[0027] To begin the coking cycle described above the closure member 120is moved laterally to close the vessel bottom by operating the actuators125, such as hydraulic cylinders 130 that are, preferably, automaticallyand remotely operable. When the closure member is moved into the fullyclosed position the closure housing 115 is purged with nitrogen and/orsteam via inlet valves 155 mounted in the closure housing body 115.Coking then begins by the process described above. During the cokingphase of the coking cycle block pressure steam is injected into theclosure housing body at a rate sufficient to maintain pressure at alevel to effectively eliminate hydrocarbon leaks at the closuremember/closure housing seat 160. Blocking steam pressure and flow rateare continuously monitored during the coking phase by use of pressureand flow rate measuring devices 165 installed in the closure housing 115and connected to a remotely located control unit 70.

EXAMPLE

[0028] In a coking vessel used for delayed coking of heavy petroleumhydrocarbon feed stocks, after about 24 hours of operation sufficientcoke is accumulated in the vessel such that removal of the coke isrequired before coking operations can continue in the vessel. At thispoint the heated heavy hydrocarbon feed is redirected to an adjoiningempty coke vessel. The full coke vessel which is equipped with a lowerspool transition piece, a closure unit and attached coke chute operatedin accordance with a preferred embodiment of this invention, is shutdown, quenched, depressurized and the closure member within the closurehousing unit is hydraulically moved laterally to open the coke vesselbottom. Hydraulic movement of the closure member is actuated by workersfrom a safe, remotely located control system. Important characteristicsof the coker vessel used in preferred embodiments of the presentinvention that can be repetitively cycled through the coking anddecoking process without removing the closure unit and coke chute,include: A coker lower flange equal to 72 inches in diameter; a flangedspool transition piece wherein the top flange of the spool piece is 72inches in diameter and the bottom flange is 60 inches in diameter; ahydrocarbon feed inlet line installed laterally on the spool piece; aclosure housing with a 60 inch diameter opening therein; a closuremember laterally moveable by hydraulic means within the closure housing;a coke chute 60 inches in diameter attached to the bottom opening of theclosure housing; and a 60 inch stroke closure member hydraulic actuatorpowered by a 3000 psi pump.

[0029] Referring again to the coking process steps, upon redirection ofthe hydrocarbon feed from the full coker vessel to the empty cokervessel, 4000 pounds per hour of steam at 150 psi is injected into thefull vessel via the laterally installed inlet line. The steam stripsuncoked hydrocarbon from the vessel which is routed to the fractionator.After a period of time, usually about two hours, the vessel is isolatedfrom the fractionator and depressurized through a relief system.Stripping steam is thereafter continued for an additional hour andthereafter quench water is added to the vessel at a slow rate to coolthe coke bed to approximately 200° F. Upon cooling the vessel to thedesired temperature the water is drained from the vessel via the inletline or by, partially or fully, opening the closure member in theclosure housing to drain water from the vessel into the coke receivingarea.

[0030] Once the coke bed is cooled and the water drained, the vessel isprepared for drilling coke from the vessel with the hydraulic drillsystem. The closure member within the closure housing is openedhydraulically by remote actuation thereby allowing the drilled coke tofall into the coke chute which is attached to the bottom of the closurehousing. As the coke is drilled it falls out of the vessel into the cokechute and is directed into the coke pit. Upon completion of the drillingprocess the hydraulic drill stem is removed from the top of the vessel,the vessel top head is replaced and the inlet line and coke vessel arevisually inspected for plugging. Once the inspection is complete and theremoval of coke and absence of plugging is verified, the closure memberwithin the closure housing is hydraulically closed. Then steam isinjected into the vessel to purge air and pressure the vessel to testthe integrity of the top head seals, inlet line seals, closurehousing/vessel/spool seals, and the closure member seals within theclosure housing. Finally, the vessel is preheated to about 400° F. to600° F. skin temperature. When the desired temperature is reached theresid hydrocarbon feed is switched into this vessel and the adjoiningvessel is prepared for decoking in accordance with the above process.

[0031] Thus, according to a preferred embodiment of the presentinvention, a delayed coking method and coke vessel have been providedwhich allow the automatic, safe, quick, and effective opening andclosure of coke vessels, or the like. While the invention has beenherein shown and described in what is presently conceived to be the mostpractical and preferred embodiment thereof, many other modifications maybe made within the scope of the invention, which scope is to be accordedthe broadest interpretation of the appended claims so as to encompassall equivalent structures and methods. For example, the structures ofthe invention may be reduced in size by a factor of two, thus making itabout 36 inches in nominal size, inverted, and applied in like form butsmaller, to provide the highly desired automation of the flanged closureon the top of the vessel.

What is claimed is:
 1. A process for repetitively producing and removingcoke from a delayed coker vessel, wherein the coker vessel has a bottomportion defining an aperture through which coke is released, comprising:(a) Sealing an aperture closure housing to the bottom portion of thecoker vessel; (b) moving a closure member within the closure housing toclose the aperture; (c) feeding a heavy hydrocarbon feed into the cokervessel through a feed line attached to the coker vessel at a positionabove the bottom of the coker vessel; (d) coking the heavy hydrocarbonin the coker vessel; (e) moving the closure member within the closurehousing to open the aperture to allow coke removal from the cokervessel; and (f) releasing coke through the aperture, and; (g) repeatingsteps c through f successively.
 2. The process in of claim 1 whereinstep (c) further comprises attaching the feed line to the coker vesselat a side entry position.
 3. The process in of claim 1 wherein step (a)further comprises sealing a transition spool piece to the coker vesselbottom and attaching the feed line to the spool piece at a side entryposition.
 4. The process of claim 1 wherein step (a) further comprisesforming a seal between the aperture closure housing and the bottomportion of the vessel wherein the seal withstands pressures within thevessel from atmospheric to 500 psi.
 5. The process of claim 4 whereinstep (a) further comprises forming a seal between the aperture closurehousing and the bottom portion of the vessel wherein the seal withstandsvessel temperatures through repetitive coking/decoking cycles rangingfrom −50° F. to 1000° F.
 6. The process of claim 1 wherein step (a)further comprises sealing a coke chute to a bottom portion of theaperture closure housing.
 7. The process of claim 1 wherein step (a)further comprises placing a gasket between the bottom portion of thevessel and closure unit and pressure-tightly joining the vessel bottom,the gasket and the closure unit.
 8. The process of claim 2 wherein step(a) further comprises placing a gasket between the bottom of the closureunit and the coke chute and pressure-tightly joining the closure unit,the gasket and the coke chute.
 9. The process of claim 7 or 8 whereinthe gasket comprises an annular corrugated metal bonded to a graphitematerial.
 10. A process in accordance with claim 6 wherein the processfurther comprises using the chute to assist in directing coke removedfrom the coker vessel into a coke receiving area.
 11. A process inaccordance with claim 1 wherein steps (b) and (e) further comprisemoving the closure member by a powered actuator or a plurality ofpowered actuators.
 12. The process of claim 11 wherein said poweredactuators are remotely actuated.
 13. A process in accordance with claim1 wherein the coking step (d) is carried out at a temperature between900° F. and 1100° F., the opening step (e) is done at a temperaturebetween '50° F. and 110° F., and the valve is selected to withstandrepeated operation at temperature cycling between step (d) and step (e).14. A process in accordance with claim 1 wherein the closure member ofsteps (b) and (e) is a valve.
 15. A process in accordance with claim 14wherein the valve is selected from a gate valve, a ball valve, a slidevalve, a knife valve or a wedge plug valve.
 16. A process in accordancewith claim 1 wherein the aperture opens to a diameter between 30 and 90inches.
 17. A process in accordance with claim 1 wherein the closurehousing and closure member are mounted to a weight bearing structureselected from the group consisting of a gantry system and a trolleysystem.
 18. The process of claim 17 wherein the closure unit islaterally removable from the coker vessel by means of said weightbearing structure.
 19. A coker vessel comprising: (a) a vessel having aflanged side aperture and a flanged bottom aperture; (b) a flanged feedpipe fitted to said flanged side aperture; (c) an aperture closure unitfitted and sealed to said bottom aperture; (d) a closure member moveablewithin said closure unit; (e) A coke chute sealed to the bottom portionof the closure unit for directing coke from the vessel to a receivingarea.
 20. The coker vessel of claim 19 wherein the closure membercomprises a valve.
 21. The coker vessel of claim 20 wherein the valve isa gate valve, a ball valve, a slide valve, a knife valve or a wedge plugvalve.
 22. The coker vessel of claim 20 wherein the valve furthercomprises a power actuated valve.
 23. The coker vessel of claim 20wherein the bottom aperture is from 30 to 90 inches.